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Copper powder and electrically conductive paste, electrically conductive coating, electrically conductive sheet, and antistatic coating using same

a technology of copper powder and electrical conductive paste, applied in the field of copper powder, can solve the problems of increased seat weight, impaired flexibility of resin sheet, uneven dispersion state of metal filler in the resin, etc., and achieve excellent uniform dispersibility, suppressed increase in viscosity, and high electric conductivity

Inactive Publication Date: 2017-05-25
SUMITOMO METAL MINING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The copper powder in this patent has high electric conductivity, and can be used as a metal filler in electrically conductive panels, resins for electromagnetic wave shielding, and antistatic coatings. It is easy to disperse and doesn't become too thick, making it suitable for use in a variety of applications.

Problems solved by technology

However, in such a case of dispersing a metal filler in a resin and applying the resin or processing the resin into a sheet, the dispersion state of the metal filler in the resin is not uniform, and thus a method is required to eliminate the problem by increasing the filling factor of the metal filler in order to obtain electromagnetic wave shielding efficiency.
However, in this case, problems that the flexibility of the resin sheet is impaired and the like are caused as well as the weight of the seat increases by the addition of a large amount of metal filler.
However, even in the case of forming an electrically conductive layer on the surface of titanium dioxide by such a method, the conductive properties are in a limited state since the electrically conductive layer is formed on titanium dioxide of a nonconductor so that a material which is far inferior in electric conductivity to a metal is used.
In particular, the miniaturization of an oil-retaining bearing and the like has progressed, and the oil-retaining bearing and the like are required to be porous, thinned, and complicatedly shaped along with this.
However, in the case of using a dendritic copper powder in an application as an electrically conductive paste, the particle size of an ordinary dendritic copper powder is significantly large.
As described above, in the case of utilizing a copper powder as a metal filler of an electrically conductive paste, a resin for electromagnetic wave shielding, an antistatic coating material, or the like, although a copper powder having a dendritic shape is optimal for securing high electric conductivity, there is a problem that the dendritic copper powders are intertwined with one another causing aggregation and the dendritic copper powders are thus not uniformly dispersed in the resin and the viscosity of the paste increases due to aggregation causing a problem in wiring formation by printing on the other hand.
In addition, as an antistatic application as well, a metal filler has not been suitable from the viewpoint of colorability.
In this manner, there have been no copper powders that can achieve both contradictory properties.

Method used

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  • Copper powder and electrically conductive paste, electrically conductive coating, electrically conductive sheet, and antistatic coating using same
  • Copper powder and electrically conductive paste, electrically conductive coating, electrically conductive sheet, and antistatic coating using same
  • Copper powder and electrically conductive paste, electrically conductive coating, electrically conductive sheet, and antistatic coating using same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0099]A titanium electrode plate having an electrode area of 200 mm×200 mm and a copper electrode plate having an electrode area of 200 mm×200 mm were installed in an electrolytic cell having a capacity of 100 L as the cathode and the anode, respectively, an electrolytic solution was put in the electrolytic cell, and a direct current was applied to this, thereby precipitating a copper powder on the cathode plate.

[0100]At this time, a solution having a composition in which the concentration of copper ion was 10 g / L and the concentration of sulfuric acid was 100 g / L was used as the electrolytic solution. In addition, polyethylene glycol (PEG) having a molecular weight of 400 (manufactured by Wako Pure Chemical Industries, Ltd.) was added as an additive to this electrolytic solution so as to have a concentration of 500 mg / L in the electrolytic solution, and a hydrochloric acid solution (manufactured by Wako Pure Chemical Industries, Ltd.) was further added thereto so that the concentra...

example 2

[0105]A copper powder was precipitated on the cathode plate under the same conditions as in Example 1 except that polyethylene glycol (PEG) having a molecular weight of 400 was added as an additive to the electrolytic solution so as to have a concentration of 1000 mg / L and a hydrochloric acid solution was further added thereto so that the concentration of chlorine ion was 50 mg / L.

[0106]The shape of the electrolytic copper powder thus obtained was observed by the method using a scanning electron microscope (SEM) described above, and as a result, the copper powder thus precipitated was a copper powder having a dendritic shape constituted as elliptical copper particles having a size of from 0.2 μm to 0.5 μm in diameter and 0.32 μm in average thereof and from 0.5 μm to 2.0 μm in length and 1.4 μm in average thereof gathered. In addition, the crystallite diameter of the elliptical copper particles was 1956 Å.

[0107]In addition, the average particle diameter of the dendritic copper powder ...

example 3

[0108]A copper powder was precipitated on the cathode plate under the same conditions as in Example 1 except that the electric current was applied so that the current density of the cathode was 10 A / dm2.

[0109]The shape of the electrolytic copper powder thus obtained was observed by the method using a scanning electron microscope (SEM) described above, and as a result, the copper powder thus precipitated was a copper powder having a dendritic shape constituted as elliptical copper particles having a size of from 0.2 μm to 0.5 μm in diameter and 0.48 μm in average thereof and from 0.5 μm to 2.0 μm in length and 1.8 μm in average thereof gathered. In addition, the crystallite diameter of the elliptical copper particles was 1105 Å.

[0110]In addition, the average particle diameter of the dendritic copper powder formed as the elliptical copper particles gathered was 18.2 μm. In addition, it was confirmed that a dendritic copper powder having a size of from 0.5 μm to 2.0 μm in thickness (di...

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Abstract

To provide a copper powder exhibiting a high electric conductivity suitable for a metallic filler used in an electrically conductive paste, a resin for electromagnetic shielding, an antistatic coating, etc., and having excellent uniform dispersibility required for forming a paste so as to inhibit an increase in viscosity due to flocculation. This copper powder 1 forms a branch shape having a plurality of branches through the conglomeration of copper particles 2. The copper particles 2 have a spheroidal shape, with diameters ranging from 0.2 μm-0.5 μm, inclusive, and lengths ranging from 0.5 μm-2.0 μm, inclusive. The average particle diameter (D50) of the copper powder 1 in which the spheroidal copper particles 2 have conglomerated is 5.0 μm-20 μm. By mixing this tree-branch-shaped copper powder 1 into a resin, it is possible to produce an electrically conductive paste, etc., exhibiting excellent electric conductivity, for example.

Description

TECHNICAL FIELD[0001]The present invention relates to a copper powder, more particularly, to a new dendritic copper powder that is composed of a cluster of fine copper particles having a single crystal structure and can improve electric conductivity by being used as a material for an electrically conductive paste and the like.BACKGROUND ART[0002]A paste such as a resin type paste or a calcined type paste using a metal filler such as a silver powder or a copper powder is frequently used in the formation of a wiring layer, an electrode, and the like in an electronic device.[0003]A metal filler paste of silver or copper is applied or printed on various kinds of substrates of an electronic device and the like and then subjected to a treatment of heat curing or heat calcination to form an electrically conductive film constituting a wiring layer, an electrode, or the like.[0004]For example, a resin type electrically conductive paste is composed of a metal filler, a resin, a curing agent, ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C09D5/32H05K9/00C09D7/12C09D161/06B22F1/00C09D5/24B22F1/052B22F1/06C09D7/61
CPCC09D5/32B22F1/0014C09D5/24C09D7/1291C09D7/1275C08K2201/005H05K9/0081B22F2301/10B22F2304/10C08K7/00C08K2201/001C09D161/06B22F1/00C09C1/02C09D201/00C25C5/02H01B1/22H01B5/00H01B1/026C09D7/68C09D7/70C09D7/61B22F1/052B22F1/06
Inventor OKADA, HIROSHIYAMASHITA, YU
Owner SUMITOMO METAL MINING CO LTD
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